Is There a Reverse Coattail Effect?

Is There a Reverse Coattail Effect?

Posted on Mar. 30, 2021

Run for Something, a Democratic organization that supports first-time candidates, has just released a study that claims that running Democratic candidates in areas with uncontested state legislative races produced a slight boost for Biden (.3 – 1.5%) in 2020.  You can find the full results of the study here.

The Run for Something (RFS) “reverse coattail effect” study gives rise to a number of concerns, including deficiencies in the data, inadequate controls, and, perhaps most importantly, the findings themselves. When RFS used the Targetsmart 2020 Partisanship Score as the primary measure of partisanship, the finding was not statistically significant.

The primary endpoint of the study was an increase in vote share for Biden. The study did not examine turnout. It is likely that contested state legislative races increased turnout on both sides. In that circumstance, it would undermine the vote share for Biden.

The study also does not discuss the effect on vote share for Democratic candidates running in other downballot races. What does the data say about having a full Democratic slate? Measuring those synergies would be useful and relevant to RFS’s work.

John Loewenstein, Swing Left Greater Boston/Swing Blue Alliance’s Director of Research, comments on the study:

The main issue is that Dems are more likely to run in districts where they were more likely to be competitive.  The authors recognized that and used two partisanship scores (TargetSmart score and Clinton share in the 2016 election) in an attempt to control for it.  The TargetSmart score did not result in a statistically significant result.  It would not be wise to assume that a trend is conclusive (but not significant) because RFS thought it would be.  More likely the TargetSmart score is a better predictor than the results of one very unusual election.  Even if there is no consistent “reverse coattails” effect it may be worth running Democratic candidates everywhere possible for other reasons.

Even if there is no consistent “reverse coattails” effect it may be worth running Democratic candidates everywhere possible for other reasons.